West, Ian M. 2014. Sarsen Stones and Erratics of the Wessex Coast. Internet site: http://www.southampton.ac.uk/~imw/Sarsens-Erratics.htm. Version: 13th January 2014.
Sarsen Stones and Erratics of the Wessex Coast, and adjacent land areas

Ian West,

Romsey, Hampshire
and Visiting Scientist at:
Faculty of Natural and Environmental Sciences,
Southampton University,

Webpage hosted by courtesy of iSolutions, Southampton University
Aerial photographs by courtesy of The Channel Coastal Observatory , National Oceanography Centre, Southampton.

|Home and Contents | Field Guides Introduction |New Forest Geology Bibliography | | Solent Bibliography |Solent - General Introduction |Brownwich Cliff, Chilling Cliff and Hill Head (with sarsens) |Solent Shores Field Guide |Solent Bibliography - General |Solent Bibliography - Topics, Alphabetically |Submerged Forest, Hayling Island |
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A sarsen stone emerging from the base of Gravel Terrace 2, Chilling Cliff, Solent Estuary near Fareham, photograph by Gary Manning, 2011

Labelled version of a photograph of a sarsen in Pleistocene gravel, emerging from a cliff, Chilling Solent Estuaries, southern England, 2011

Sarsen on a beach of Langstone Harbour, Solent Estuaries, southern England

A large sarsen stone in Portesham church, Dorset

A large sarsen stone with striations on the beach below Chilling Cliff, northwest of Hill Head, Hampshire, Solent coast, 2007

Root moulds descending from small root holes in a sarsen of the common, small-root-hole type, preserved in the centre of Titchfield, Hampshire

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Sarsen stones are blocks of quartzite, often found above the Chalk, and most famous for their use at the major stones of Stonehenge (in addition to the Bluestones - dolerite). This webpage is concerned with those on the Wessex coast and adjacent area, with some inland examples also included.

Sarsens are very abundant in the Solent area, particularly from the coast at Chilling, near Fareham, southeast to Selsey Bill. They are particularly features of the low-level Pleistocene gravel terraces and the low-level raised beach of the Selsey peninsula. The Solent type of sarsens are not very large, often about a metre in length and with a thickness of about 60cm. They are usually joint-bounded and often with moulds of tree roots and small roots of shrubs. They mostly consist of medium sand of quartz, cemented by quartz.

The source area for the sarsen stones of the Solent has not been determined. Their common occurrence in southern England above the Chalk indicates a Tertiary origin. No quartzite is known in the Tertiary of the Hampshire Basin or Solent area. However, Tertiary quartzite is present at the southeastern margin of Dartmoor (Bristow, 1993). The sarsen stones of quartzite with roots are similar to ganister, a type of siliceous seatearth found under coal seams in the Carboniferous. It is interesting that there are coal seams in the Eocene of Alum Bay and Whitecliff Bay, but where exposed these do not have quartzites beneath. However, there is a palaeosol with roots beneath the example at Whitecliff Bay. Furthermore, it contain a tonstein ( recrystallised kaolinite), a feature of some Carboniferous coals, and this is a good indication of the very low pH conditions that could be involved in the transport and reprecipitation of silica. Thus ganisters might have been present under similar Tertiary coal seems elsewhere in the region (perhaps in the southern Isle of Wight or the nearby English Channel area.

Some of the old discoveries of sarsen stones, like the Southampton stones shown above, are not widely known. Attention is drawn to these and also to many of the examples still accessible around the Solent (and more illustrations will be added, progressively).

In addition to those on the surface, some discoveries of large sarsen stones have been made under water in the eastern Solent or Spithead south of Portsmouth and offshore south of Hayling Island by Dr Ken Collins and by John Barber and his diving team. They may be similar to those onshore at Hayling Island, but detailed study has not yet been made. There are also many sarsen stones at the Dolphin Bank on the western side of the Isle of Wight (Dr. Ken Collins - personal communiction). Undoubtedly there are many more sarsen stones offshore which have not yet been found or recorded.

In addition to the common sarsen stones, there are also erratics (i.e. rocks foreign or strange to the area) of other material on the Sussex-Hampshire coastal plain. These include quartz-cemented sandstone, granite, syenite, "greenstone" and several other rocks types They are found in the low-level Pleistocene raised beach extending from Gosport to Selsey Bill and on eastward to the Brighton area. See for example Cordiner (2006) , on the erratics of Chichester Harbour). Many have been seen on the coast, sometimes about 30 at a time, and probably thousands lie buried under the coastal plain. Similar erratics also seem to occur offshore, and have probably been eroded from the raised beach. Some, submerged examples, however, could have been associated with lower Pleistocene sea-levels, and this has not been investigated.

Geological literature referred to below shows that the erratics have been deposited in the region not less than about 128 thousand years BP and are associated with Pleistocence deposits containing elephant remains. There has been some discussion about whether the erratics were deposited by floating ice or by glacial ice of an English Channel glacier. Igneous rocks present near Chichester, Pagham and elsewhere can be linked to northwestern France and the Channel Islands, but there has also been discussion about whether material has been transported from the North Sea. The text and diagrams below are not to provide answers but simply to introduce some background information, on the basis of which further discussion of the erratics can take place. The important new discoveries and searches of the sea-floor in progress are likely to provide important new information on the distribution and origins of the erratics.

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Early Records

Erratics exposed by the 1891 storm, Medmerry, Selsey, Sussex

Mr. Godwin-Austen reported the presence of erratics on the Hampshire-West Sussex coastal plain in 1857. Thomas Codrington referred to them in 1870. They were noted in a well-known student text book of Sir Charles Lyell in 1871 and major discussion at the Geological Society of London took place with regard to these in 1892 by the distinguished geologist, Sir Joseph Prestwich and by Clement Reid, who did much geological surveying in the region.

Some locations where sarsen stones and/or erratics occur are given below, generally from east to west.

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At Brighton there is the well-known raised beach with above about 20m of head with elephant, rhinoceras, hippopotamus etc. The beach consists of well-worn and well-rounded flint-shingle, mixed with sand and some Tertiary flint-pebbles, together with pebbles and worn blocks (mostly small) of older rocks. Mollusc shells include Cardium edule, Mytilus edulis, Littorina littorea and Purpura lapillus. A jawbone of a whale has been found at the base of the shingle. There is a varied assemblage of unusual rock types amongst the pebbles, but they are mostly as small and worn specimens. They include granites, syenite, porphyry, quartzite, mica-schist and various sandstones. The West Sussex coastal plain, further to the west has raised beach deposits, flint gravels, chalk rubble, head and brickearth. Mammoth remains occur at Worthing and Peppering, near Arundel.

The remaining exposures of Brighton raised beach at Black Rock have been discussed in a report on a field meeting by Ullyott, Whiteman and Nash (2000). They mentioned that recent work suggests that the raised beach does not date from the last interglacial (Oxygen Isotope Stage (OIS) 5e), as previously thought by West and Sparks (1960), for example. Amino-acid geochronology of shell fragments from the raised beach indicated an OIS 7 (c. 200 ka BP) date (Davies, 1985). Ullyott et al. (2000) mentioned that this supports new mammalian evidence in the form of a horse Equus ferus, which at both Brighton and Portslade to the west, is significantly smaller than both younger and older horses (Parfitt et.al., 1998). Ullyott et al. (2000) also refer to large sarsen stones in head above the raised beach.

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Between Worthing and Pagham, in addition to the pebbles of unusual rocks as present at Brighton, there are considerable numbers of large boulders. A block of fine-grained granite, measuring 0.8m by 0.5m was found near Barnham Farm (Prestwich, 1892). The boundary stone at Rustington is an erratic covered with marine growth and probably of French origin, which has been brought inland from the seashore (Kellaway et al. 1975). Occasional blocks occur in the direction of Chichester. The "foreign" boulders are found in greatest number and of largest size around Pagham Harbour. Godwin-Austen (1857) mentions:-
grey porphyritic granites, compact red granites, syenite, hornblendic "greenstone", mica-schist, green fissile slates, "fibrous chloritic semicrystalline rocks", masses of vein-quartz, siliceous sandstones, conglomerates, micaceous sandstones with Orthidae(i.e. Lower Palaeozoic), black micaceous shaly sandstones, and compact limestones (details not given).

One block of porphyritic red granite, which had fallen out of the low cliff, was 8.4m in circumferance.

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Selsey Bill

Boulders of up to 10 tonnes were formerly abundant at Selsey Bill but there are rarely visible at the present time owing to the effects of marine erosion and encroachment of the shingle (Kellaway et al. 1975). Purbeck silicified wood has been reported by Fisher (1871) at Selsey.

The largest collection of mammalian remains associated with the raised beach comes from Selsey. They Elephas antiquus, Elephas primigenius, Rhinoceras tichorhinus, Equus caballus, Bison priscus, Bos longifrons, Cervus elaphus and Canis lupis. Shell beds of the raised beach occur in places (Prestwich, 1892).

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Selsey - continued - Medmerry Coast, West of Selsey Bill

Raised beach west of Selsey Bill, Sussex Pebbles orientated vertically in the raised beach, west of Selsey Bill, Sussex

A coastguard station with a prominant tower is situated on the western side of Selsey Bill, not far from Crablands Farm and from the Medmerry Windmill and the large caravan park. The map reference of the coastguard station is SZ 845930 and it is clearly marked on the Ordnance Survey map - Explorer 120 - Chichester, South Harting and Selsey, 1:25,000. There are concrete sea-defences at the coastguard station but to the northwest there is an eroding coast with a low cliff. This reveals an excellent section in the Ispwichian (last interglacial) raised beach deposit of rounded pebbles, as shown in the photographs above. Over this is brown brickearth, which when unweathered can be calcareous with chalk solifluction debris. In normal conditions it is not usually possible to see what lies beneath the raised beach pebble bed. The present beach obscures the lowest part. At very low tides after exceptional storms more may be revealed. In late Victorian times there was much interest in the discovery here of a two ton mass of Bognor rock with striae like those in glacial deposits.

In 1892 Clement Reid discussed an unusual exposure of erratics at the base of the Ipswichian raised beach deposit at Medmerry. The exposure resulted from a storm of October 24th in 1891.

Erratics exposed by the 1891 storm, Medmerry, Selsey, Sussex

"During the continuous south-westerly gales of last autumn and early winter, the loss of land on the west side of Selsey Bill was extremely great. Not only was the cliff line cut back several yards, but the scour was so strong as to remove most of the beach and lay bare platforms of Eocene and Pleistocene strata at a level where we usually find nothing but beach-shingle. Immediately after the storm of Oct. 24th I re-examined the coast close to Selsey, and found that erosion had been particularly marked opposite Medmerry Farm, where the sea had undermined one corner of the farm buildings, though in 1898 it was about 20 yards away. This cutting back of the cliff, and the concurrent removal of most of the beach on the foreshore opposite, exposed a section unlike anything which had been seen, though the unusual abundance of large erratics on the foreshore had always led me to suspect that this was the critical point, and that there was a probability of finding the glacial deposit in place in the immediate neighbourhood.

Below the level of mean tide there was seen only a wide expanse of fossiliferous Bracklesham Clays full of Corbulae [note that Corbula is abundant in the Cypraea Bed or Brook Bed, S6 to S9 of the Selsey Formation, Bracklesham Group, which crops out quite close to Medmerry Windmil - see Curry et al. 1977], but at a level slightly higher, on the part of the foreshore first laid bare by these storms, the junction of the Eocene and Pleistocene strata was exposed. The relations of the two deposits were so peculiar as to at once attract attention. The junction was neither smooth nor channelled, as is ordinarily the case, but the whole surface of the hard Eocene clays, for a quarter of a mile, was full of basins or pits from 2 to 6 feet [about 2 metres] across. These pits were usually unconnected with each other, and strike one as a feature totally unlike the irregular eroded channels formed by running water between tide-marks. Many of the pits had nearly vertical sides and were 2 feet or more in depth, but it was difficult to ascertain the extreme depth, for on each occasion when the section was well-exposed the pits were full of water, and time and the tides would not allow me to bale out or drain many of them.

Four out of every five of the basins contained nothing but loose gravel, with a few valves of Balanus and rare fragments of marine mollusca. The loose material, except where cemented by iron oxide, has been almost entirely removed by the recent storms, which were not able to make much impression on the harder Bracklesham Clays. The remainder of the basins were much more interesting, for each contained an erratic block, which had not merely been dropped, but showed signs of having been forcibly squeezed or screwed into the clay, until its upper surface was flush with the general level. In this process the softer and more splintery rocks had been crushed, so that they are now found with their angular fragments slightly separated by gravel, or by fossiliferous Eocene clay. The harder masses were driven into the clay so that I was obliged to cut away fossiliferous Eocene clay to get out the Pleistocene erratic. It seems clear that most of these pits are not hollows eroded by water, but dents made by the ice or by erratics; for the stratified Eocene clays generally become much disturbed and contorted around the margin of the hole. The pits filled with finer material probably mark the spots where large erratics were formerly deposited, though, becoming again frozen into the ice-foot, they were lifted out and transported to fresh sites.

About a hundred of these pits were examined, and the conclusion seemed irresistible that they afforded clear evidence of the agency of floating ice. Drift-ice grounding on the ancient foreshore dropped its burden of erratics between the tide marks. Here they were pressed deeper and deeper into the clay, for the rise and fall of the tide at high-water piled ice upon any projecting rock, while at low water the rock was pressed down by the weight of the ice till it was flush with the general surface. Often, however, the still-projecting boulder would be firmly frozen into a new ice foot, or accumulated mass of pack-ice, and would then be gently lifted out of the hole at the rise of the spring tides. It is thus that I account for the occurrence of emptly pits, for they seem to mark the former sites of blocks which may have shifted their position several times before finally coming to rest. Perhaps some of the basins were produced by the stranding, packing and revolving of masses of ice during a storm, but the general appearance of the section suggests tranquil water in a sheltered bay. No signs of furrows ploughed in the clay were observed, and the ice was probably entirely in the form of flat-bottomed ice-foot, which, at a spot like this, sheltered from the prevalent winds by the Isle of Wight [but note that the prevalent wind-direction then is not known], would ground gently and would tranquilly melt away without being driven violently into the shoals, as on a more exposed coast."

Erratics belonging to the following rock types were recorded by Reid . See the original paper for more accurate measurements, which are given in feet and fractions of feet.

1. Bembridge Limestone, cream-coloured and with moulds of Limnaea [Galba ]. Four blocks studied, mostly about a third of a metre in length.
2. Bognor Rock, from the London Clay of the Bognor area (Bognor Ledge). Hard sandstone or calcareous grit, usually with Pectunculus brevirostris. Six blocks, some almost 2 metres in length. One block was bored. One large block was 5 feet by 4 feet and probably weighed more than 2 tons. This contained Pectunculus brevirostris and Voluta denudata and had been striated by ice. There is a photograph in Reid's paper.
3. Sarsens. Tertiary quartz-cemented sandstone. Four blocks, about a third to half a metre in length.
4. Black Flints from the Upper Chalk. Size was not specified.
5. Upper Greensand, probably from the Isle of Wight. Glauconitic sandstone, some cherty and some phosphatic, and also dark-coloured chert with sponge spicules. One large block of glauconitic sandstone was more than 2 metres in length. Most of the others were of about a third of a metre in length.
6. Hard pale green and reddish sandstone, probably Palaeozoic. About half a metre in length.
7. "Greenstone". Palaeozoic. About a third of a metre in length.
8. Granite of muscovite-biotite type. About a third of a metre in length.

Compared to a list of the rock types which have been found as erratics in the deposits of the neighbourhood of Selsey, the Medmerry rocks are unusual in including a predominance of erratics from localities within 20 miles of Selsey. The general list for the region includes many igneous rocks. Reid suggested that the local rocks, being less resistant, have in many cases disintegrated at some stage. Thus in time the harder igneous rocks become proportionally more dominant. Medmerry is important in revealing the original relative abundance of local material.

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Bracklesham Bay

Erratics of various foreign rocks, including basalt, diorite, syenite, granite, gneiss, etc., ranging up to 1.5m in maximum diameter and sarsens attaining greater dimensions, occur on the shore of Bracklesham Bay near Cakeham and East Wittering. They are occasionally seen in the low cliffs (White, 1915).

The fossiliferous mud-deposit of West Wittering occurs east of the entrance to Chichester Harbour. It crops out on the shore to west of West Wittering beacon but is obscured for long periods by accumulations of sand and shingle. There is an ancient eroded channel with Rhinoceras and Elephas, together with Corbicula fluminalis, Succinea oblonga and Hydrobia marginata (Reid, 1891 in White, 1915). The gravelly base is full of redeposited erratics. White marl with chalk grains was seen above this gravel at one place.

Important evidence for the age of the stones comes from West Wittering where peaty clays above the gravel with erratics is fossiliferous. This topic is discussed in the Dating of the Erratics Section".

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Chichester Harbour

An exfoliating mass of pink granitoid rock measuring 1.8m by 1.5m by 0.9m was found west of the hardway on the north side of Chichester Channel at Itchenor Ferry. A block of speckled grey rock, approximately 3.1m by 1.7m by 1.4m was seen on the foreshore of bare London Clay 0.4m west of Longmore Point (White, 1915). Incidently this boulder was apparently not visible in 1891. In May 1914 it was 22.9m distant (seaward presumably) from the face of the cliff (White, 1915). This was the largest erratic in the area covered by the Lymington and Portsmouth Geological Survey Memoir. It shows sign of rapid distintegration along gaping fissures, and at its eastern end lie four detached masses (ranging up to 1.37m in diameter), which when in position probably added another 0.45m to 0.6m to its total length (thus it was originally about 2.3m in length).

White (1915) submitted the rock for petrographic study. Dr H.H. Thomas contributed the following note on the basis of a petrographic examination:

"E 11220. The specimen submitted has been sliced and proves to be a much crushed Quartz diorite. The rock has no similarity with anything in the south of England and Wales, except perhaps with some of the Pre-Cambrian Quartz diorites of Pembrokeshire. Quartz-diorites are common in the Channel Island and the North of France, and these localities would seem to furnish a more likely source than Pembrokeshire, especially as other boulders have been found on the South Coast, which, with good reason, have been considered to be of extra-British origin" - H.H.T.

It is just appropriate to note at this point that the Stonehenge Bluestones, although not diorites, are dolerites supposedly from Mynydd Preseli in Pembrokeshire.

The gravel from which the diorite probably came is well exposed in an adjacent cliff (figured by White, 1915), and has much in common with the erratic gravel of the Medmerry Farm section (Bracklesham Bay). It is coarse in texture, contains much Bognor Rock (from the London Clay) and some small blocks of Bembridge Limestone. There are also other igneous rocks and quartzites etc. The gravel occupies a group of basin-like indentations, 1 to 3m wide, in the London Clay. White (1915) comments that the indentations are clearly due to vertical pressure exerted by or through the contained mass of gravel, for the London Clay, which is well-stratified has adapted itself to their shape by flexing and shearing, with a development of slickensides at and about the contact with the gravel. In many cases the gravel on the bottom and sides of the basins is cemented by tufa into a hard crust, 2.5cm to 7.6cm thick, which is apt to persist as a jagged ring on the shore for some time after the waves have cleared out the rest of the gravel and planed away the surrounding clay (White, 1915). These indentation could be the result grooving of the sea floor by ice (cf. Belderson, Kenyon and Wilson, 1973). The distortion of the London Clay is, no doubt, due to an overburden of ice. The question is how much ice - that of a glacier (cf. Kellaway, 1975) or a stranded ice-floe?

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Hayling Island

(See also: Submerged Forest, Hayling Island )

The surface of Hayling Island is flat with about a metre of so of gravelly clay lying on London Clay, with large boulders occasionally projecting above the surface (Prestwich, 1892). Large boulders are common on the coast and many are seen inland. Prestwich reported: fine-grained white granite, red granite, syenite, porphyry, diorite, white quartz rock, light-coloured micaceous sandstones, light-red sandstones (these are discussed further below in the section on origin), hard chalk (drilled by annelids), freshwater limestone (Upper Tertiary) [Bembridge Limestone?], silicified wood from the Purbeck Formation.

Most of the blocks are angular or subangular. A few are smooth and look ice-worn but Prestwich saw no definate markings. They were often met with in trenching and draining at a depth of about a metre. They may vary in weight from a half to 6 tons. The largest blocks were of quartz-cemented sandstone or quartzite and measured about 2m by 1.5m. by 0.8m, and 1.5 by 1.5 by 0.8m (this last was very angular according to Prestwich, 1892). 30 blocks were found on a mile of shore. They were originally more numerous because a large number had been gathered up in the grounds of Westfield House, and many may have been broken up. The silicified wood was 0.66m long by 0.35m wide. As mentioned above, a similar find has been made by Fisher (1871) at Selsey and the Portland Stone coral - Isastraea has been reported from the coast of Sussex. The boulders appear to form part of the clay and gravel drift and marine shells (Ostrea, Cardium and Littorina) may occur under the drift and boulders. Prestwich (1892) considered that the boulders were stranded on the old beach shore and latter covered by the gravel drift.

Erosion on the shore of Langstone Harbour, Hayling Island

The western shore of Hayling Island is being eroded to a limited extent by waves coming across Langstone Harbour from a southwesterly direction (in accordance with the prevailing wind). Sarsens can be seen on this harbour coast north of West Town and northeast of Sinah Warren. The map reference is SU 709003 and there is a footpath to the beach from North Shore Road, and the stones can be found quite easily a short distance north of the northern end of this road.

Sarsen on a beach of Langstone Harbour, Solent Estuaries, southern England Four sarsens on a beach of Langstone Harbour, Solent Estuaries, southern England

One of four sarsens on a beach of Langstone Harbour, Solent Estuaries

A sarsen with 'root-holes', one of four sarsens on a Langstone Harbour beach Another view of the sarsen with 'root-holes' on Hayling Island

Several sarsens are visible on the beach here. Four are aligned normal to the coast and have probably been moved into this position as some sort of boundary. Others are randomly positioned and seem to have come from the eroding cliff. As you can see from the photographs they are not particularly large. One example is interesting in presenting a flat surfae that appears to be a bedding plane and having numerous small pits or holes normal to this surface. A first impression suggests that they could have been either root moulds or burrows, but it is not obvious as to which. Some of the holes seem to be paired, but this may be a false impression. In general they resemble the root-holes shown by Hepworth (1998) in a sarsen stone from Clatford Bottom, Marlborough Downs, Wiltshire

Further comments on the erratics of Hayling Island have been given by White (1915). He mentioned that on the shore of Langstone Harbour, west of the Manor House at South Hayling, there are more than 20 boulders, mostly of fine sandstone [quartzite], but including dark hornblende-granite and biotite gneiss. Other blocks, again mostly sandstone [quartzite], were seen at and about South Hayling, on the sea-front and inland, where such stones were used in former times for building. There are good examples in the walls and yard of the parish church, and of the adjacent farm. The four stones shown above have probably been aligned by human activity, but were probably originally derived from the adjacent low cliff.

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Portsea Island (Portsmouth )

Two sarsen stones on the shore of Langstone Harbour, and on the east side of Portsea Island, south of Kendall's Wharf, 2008

Two sarsen stones were noticed on the shore of Langstone Harbour, south of Kendall's Wharf, on the east side of Portsea Island (near the sports ground and yacht club). One of these shows a conchoidal fracture, but it is not obvious as to whether this in old in geological terms or is a relatively recent fracture.

In the past, boulders at Portsea "from 1 to 2 cubic feet in size" have been reported by Codrington (1870). They include granite, syenite, "greenstone" and sarsen stone. These blocks were described as rounded and smoothed boulders, brittle from partial decomposition. Similar boulders, sarsens and large flint-nodules have been occasionally found at the base of the brickearth near Kingston and Buckland, in brickyards and trenches for the foundation of houses. A few tabular sarsens, from which the surrounding gravel and brickearth have been removed have been seen on the floor of an old working half a mile east of Baffins Pond (White, 1915). This is near the college.

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Chilling and Brownwich Cliffs and Gravel Pits, near Fareham

Sarsens - Unworn, Jointed Blocks

Sarsen stone blocks from the Pleistocene gravels are common on the beach, at about mid-tide level, at Brownwich and Chilling Cliffs to the northwest of Hillhead. They occur in Pleistocene Gravel Terrace 2. Several sarsens have also been found in a nearby gravel pit at Hook (examples removed from this pit are shown above). The gravel terrace here seems to contain many more sarsens than occur in most gravel terraces.

The sarsens here were referred to by Nicholls in 1866. For more on the geology these cliffs see the Brownwich, Chilling and Hill Head webpage.

The general characteristics of the bedded type of quartzite sarsen stones present in the Pleistocene gravels of Chilling and Brownwich Cliffs, Solent coast, near Fareham, Hampshire, and at Hayling Island, very generalised

An idealised, diagrammatic model of a Tree Root Sarsen from the Pleistocene gravels of the Solent coast

A joint-bounded, rectangular sarsen stone on the beach below Chilling Cliff, northwest of Hill Head, Hampshire, Solent coast, 2007

A quartzite outcrop at the Stiperstones, Shropshire,  probably similar to the original exposures of Tertiary quartzite that were the source of the sarsen stones of southern England

(For more on the Stiperstones go to:
Geology of Britain - Introduction.)

Large sarsen stone at Chilling Cliff, Solent coast, near Fareham, Hampshire, 30th March 2008

A large sarsen stone with striations on the beach below Chilling Cliff, northwest of Hill Head, Hampshire, Solent coast, 2007

A large angular sarsen with a cylindrical hole, Pleistocene gravel, Hook, near Fareham, Hampshire

A sarsen with rolls and a cylindrical hole, from a gravel pit in Pleistocene gravel Terrace 2 at Hook, near Fareham, Hampshire

Opposite side of the sarsen with rolls and a cylindrical hole, from a gravel pit in Terrace 2, Hook near Fareham, Hampshire

A large angular sarsen stone with rolls, from the Pleistocene gravel terrace 2 at Hook, near Fareham, Hampshire

A sarsen stone with rolls and a horizontal cylindrical hole, from a Terrace 2 gravel pit at Hook, near Fareham, Hampshire

A sarsen stone, with a hole, in a private garden at the village of Chilling, and originally from a gravel pit in the low Pleistocene terrace

An angular sarsen stone from a gravel pit at Hook, near Fareham, Hampshire

A tabular sarsen with a conchoidal corner fracture, from a gravel pit at Hook, near Fareham, Hampshire

A small angular sarsen stone at Chilling Cliff, near Fareham, Hampshire - this has fallen from the Pleistocene gravel, photo 21st October 2007

A small sharp-edged and iron-stained sarsen from Chilling Cliff,
 Solent coast, near Fareham, Hampshire, 30th March 2008

Probable root moulds in a sarsen stone from the Pleistocene gravel Terrace 2 of Hook, near Fareham, Hampshire

A small, beach-worn, sarsen stone that has been derived from Brownwich Cliff, northwest of Hill Head, Hampshire, Solent coast, photo 2004

Two of the Three Stones of Titchfield, Hampshire; sarsen stones, one of which shows the lateral termination of a quartzite lens

One of three sarsen stones from Three Stone Coppice and preserved in West Street, Titchfield, near Fareham, Hampshire; this one has moulds of large plant roots

Root moulds descending from small root holes in a sarsen of the common, small-root-hole type, preserved in the centre of Titchfield, Hampshire

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Hook, near Chilling, Hampshire
Sarsen - Nodular Silcrete Type

An ovoid sarsen stone from the gravels of Terrace 2 in a gravel pit near Hook, near Fareham, Hampshire, and now used as a garden ornament

Side view of an ovoid sarsen stone from the gravels of Terrace 2 in a gravel pit near Hook, near Fareham, Hampshire, and now used as a garden ornament

Opposite side of the ovoid sarsen stone used as a garden ornament, but from the Pleistocene gravels of Hook, near Fareham, Hampshire

The nodular silcrete or sarsen stone shown above is from a gravel pit in Gravel Terrace 2 at Hook, near Fareham. It is rather similar to the nodular silcrete lenses that occur in situ in the Oligocene Fontainebleu Sands at Bonnevault Quarry, Larchant, Seine-et-Marne, Paris Basin ( Thiry, 2001). These have been attributed to an origin that is from groundwater rather than pedogenic ( Ullyott et al., 1998). This silcrete nodule resembles in morphology the common nodules of siderite found in local Tertiary deposits, as in the Eocene of Hengistbury Head and Hordle Cliff.

Nodular silcretes have been described in the Upper Eocene to middle Miocene, Cypress Hills Formation in southern Saskatchewan, Canada (Leckie and Cheel, 2006).

Comparison between an ovoid sarsen stone from the Pleistocene gravels of Hook, near Fareham, Hampshire, and the ovoid siderite nodules of the Eocene of Hengistbury Head

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Calshot Spit and Stanswood Bay

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Calshot Spit and Stanswood Bay webpage?

A single, beach-worn, sarsen at Luttrell's Tower near Calshot Spit, the Solent, Hampshire

Relatively soft quartzite in a sarsen stone at Luttrell's Tower, Stanswood Bay, near Calshot Spit

A single sarsen stone was found on the beach in Stanswood Bay at Luttrell's Tower, Eaglehurst (map reference - SU 477009). It is near the low water mark. This sarsen is about a metre and a half in length and, in general, resembles the tabular type of sarsen found at Chilling and Brownwich Cliffs on the other side of Southampton Water. From its position in front of the tower which has been there since 1730 it has presumably been on the beach for about 300 years or more. There is no evidence of rapid erosion just here. A long period on the beach explains its eroded upper surface and the presence of potholes.

No other sarsens were observed in this area, although not all has been searched (because of a Nature Reserve closed to the public). There is much concrete debris from the World War II activities here. The cliffs are not undergoing much erosion here, except further southwest near Nelson's Place. Some large rocks are present as ornaments around a flagpole adjacent to a large hanger on Calshot Spit. However, these are not sarsens but include slickensided blocks of metamorphic rocks, and have presumably been brought into the area as ballast.

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Sarsen  Stones at Southampton, 1866

A large sarsen stone, weighing half a ton, was once visible by the side of the road at "Burgess Street" at the top of Southampton Common ( Solly, 1910). Sarsen stones have also been found in the Southampton area at Freemantle "on the present coastline" (Nicholls, 1866). Three blocks of stone were found at Bishopstoke. At Bevois Valley gravel pit, Southampton, three blocks were also found. The largest of these was 1.09 m. (43 inches) in length (Nicholls, 1866). " These three stones have been placed in the court-yard of the Hartley Institute, at Southampton, where, by the kindness of the Principal of that Institution, they may now be seen" (The Hartley Institute was the predecessor of Southampton University). "All the stones at Bishopstoke, and Nos. 2 and 3 here, were found at the bottom of the gravel. No. 1 [the largest], however, was found upright, about half-way down the gravel with about four feet of gravel above, and four below it" (Nicholls, 1866).

A block of Tertiary sandstone was found at Red-hill gravel pit, three miles from Southampton on the Winchester road and about 170 feet above the sea. It was at the bottom of the gravel (Nicholls, 1866). Between Bishopstoke and Winchester, at about 8 miles from Southampton there was said to be a large "erratic". Another large block was found near Winchester, about 12 miles from Southampton in 1864. None of the stones was scratched striated or rounded. A tortoise-shaped one and a dromedary-hump shaped stone have been separated from the parent rock by clean, straight, fresh-looking fractures in their greatest diameter, suggesting the action of very heavy ice (Nicholls, 1866 - Lieutenant-Colonel W.T. Nicholls, writing from Fulham on the 25th April, 1866).

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Pennington and Milford-on-Sea

See also: Hordle Cliff and Milford-on-Sea Webpage.

A sarsen stone on the beach near Paddy's Gap, Milford-on-Sea, Hampshire

Blocks of sarsen stone occur up to 2m in length at Pennington, near Lymington, in the low-level terrace. Sarsens also occur at Milford on Sea (Everard, 1952). A beach-eroded example is shown above.

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Isle of Wight

A raised beach occurs at intervals from Bembridge to Ryde (Prestwich, 1892). It consists of a mass of rolled chalk flints, some Tertiary flints, and white quartz pebbles, rounded fragments of ironstone, cherty Upper Greensand, and sarsenstone, with a few large pebbles of light-coloured and red quartzite, and small pebbles of "lydianstone" (i.e. lydite or Palaeozoic black chert) and slaty hornstone, in a matrix of roughly-bedded, quartz sand. No large boulders or shells have been found.

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Branksome, Upper Parkstone, Poole, Dorset

During excavations for a sewer in 1909 a large boulder was discovered in Ashley Road, Upper Parkstone, 2.4 to 2.7m (8 - 9 feet) below the surface. It was close to Scott's woodyard, near the bottom of the dip not far from the top of Constitution Hill (Solly, 1910). It was presented to the Museum of the Branksome Free Library and was there in 1910. Its length was 1.02 m. (3 ft 4 inches) and the greatest girth 1.37m (4ft 6inches). It was originally somewhat larger as some part of it was broken off before it was raised to the surface. It was in Plateau Gravel, overlying Bagshot Sand (probably Poole Formation ). The stone was a sarsen or greywether, similar in thin-section to a sarsen specimen from the Valley of Stones near Bridehead, Dorset. The surface was waterworn and had two cup-shaped depressions. Other sarsen stones have been found on the south slope of Constitution Hill, and at Pokesdown, Bournemouth (Solly, 1910).

It is interesting to note that this specimen had so many tourmaline grains that they could be seen with the naked eye. The obvious source of tourmaline is the Dartmoor granite and its aureole. Is there any distant link here to the Tertiary quartzite of Woolley, near Bovey Tracey, in southeastern Dartmoor ( Bristow, 1993)?

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Portland Raised Beaches and Portland Mammaliferous Drift

Go to: Portland Bill Webpage?

The Chesil Beach in Dorset does not have large erratics but does contain pebbles of unusual rock types. Because many ships have been wrecked there some caution is needed because some ship ballast has probably contributed to the beach. Comparison can always be made with the Portland raised beaches, though, which, of course, have no problem of contamination. The Chesil Beach contains numerous Budleigh Salterton (Bunter) pebbles, igneous and metamorphic rocks from Devon and Cornwall and far-travelled erratics (but these are pebbles, not large erratic blocks) from northern England and Scotland. As Strahan (1898) and Arkell (1947) have indicated, the non-local material can hardly be travelling round the coast line of Britain and crossing Lyme Bay in a continuous stream at the present day. Strahan suggested that derivation from local Tertiary strata is taking place, but, as Arkell pointed out, huge quantities of Budleigh Salterton pebbles and Permo-Triassic porphyry pebbles could not have been obtained from this source. The problem arises to why these rocks, mingled with Chalk flints, Greensand chert and erratics from the north of England and Scotland, be found in such quantity in the Chesil Beach. Some of these rocks could have been obtained from Permo-Triassic rocks in Devon or on the sea floor in the western part of Lyme Bay. Arkell concluded that the existing beach began its life at the beginning of the Neolithic submergence as a bay-mouth bar stetching from an extended Portland Bill westward across what is now West Bay (Lyme Bay) to join some lost headland of Cretaceous and Tertiary rocks seaward of Beer Head and Dowlands Cliff.

Kellaway et al. (1975), with their controversial English Channel glacier theory in mind, point out though that it is curious that there are very few pebbles from the rocks of Start Point or Torquay, the schists, hard Devonian grits, igneous rocks, quartzites and marmorised limestones of this area, if present, are feebly represented. They argued that a vast amount of morainic drift, partly derived from English Channel ice and partly from material brought down the Teign, Otter, Axe and other valleys was concentrated in marginal channels before being re-sorted by the advancing sea, first in Eemian (Ipswhichian) and later in Weichelian (Devensian) and Holocene (Flandrian) times. Thus the English Channel glacier theory of Kellaway et al. (1975) could explain the small pebble erratics of rock types from distant areas in the Chesil Beach. Perhaps, however, floating ice could also explain the transport of these rocks.

On Portland at a higher level than the raised beaches discussed here, at about 120m (the level of a widespread plateau on the Dorset coast) is the Portland Mammaliferous Drift (Prestwich, 1875). It occupied an irregular trough in the Purbeck and upper part of the Portland strata in the northern part of the Isle (Admiralty Quarries) and contained horse and elephant remains. Well-rounded and unusually polished pebbles occur in places at the base, suggesting that this could, perhaps, have been a raised beach although there are other possibilities. Above this level was red clay or loam passing into coarse loess. In places this deposit was full of angular debris from the Portland and Purbeck beds, together with "a considerable number of small blocks (some a quarter of a ton in weight) of the hard sandstone or sarsen-stone of the Lower Tertiaries." The sarsens were much worn an stained reddish brown, and sometimes blackened by manganese oxide.

Sarsen stones, are common in the Portesham area of Dorset (Valley of the Stones and in Portesham village) and also occur near Lulworth Cove (Arkell, 1947).

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Salcombe Hill, near Sidmouth, Devon, - Sarsens or Greyweathers

Silicified breccia and sandstone at Salcombe Hill, Devon, have attracted attention because they seem to be sarsen stones at or near their location of origin. Here is some description and comment summarised by Woodward and Ussher (1899).

"Attention was first drawn by Buckland to the occurrence of "pebbles of fat quartz" on the uplands; also to the presence of rounded pebbles of chalk flint, and near Sidmouth of "large blocks of a siliceous breccia, composed of chalk flints united by a strong siliceous cement, and differing from the Hertfordshhe pudding-stone only in the circumstance of the imbedded flints being mostly angular, instead of rounded as in the stone of Hertfordshire." He therefOl'e inferred "that there was a time when the chalk covered all those spaces on which the angular chalk flints are at this time found"; and that there is also reason to think that the plastic clay formation was nearly coextensive with the chalk."

Large blocks of this siliceous breccia may be seen on Salcombe Hill, and beach pebbles formed of it are polished and sold as " Sidmouth pebbles." The occurrence of beds of Tertiary age was discussed by Godwin-Austen (1822 and 1826 - Transactions of the Geological Society), who commented on the occurrence of siliceous breccia near Sidmouth:

"This breccia affords proof of a long post-Cretaceous period of tranquil deposition, and of a subsequent one of destruction, of both of which it is the sole remaining indication. "Besides the breccia, there are large slabs composed partly of similar materials, and in part (taking the blocks according to their thickness) of a compact, fine-grained sandstone, some blocks containing only an occasional flint, but some none at all, in which cases they are mineralogical greywether sandstones; and may probably be the equivalents of those siliceous masses, warranting, a presumption at least, that Tertiary deposits once extended wherever this breccia now occurs; for the blocks are so angular that they cannot be supposed to have been conveyed from a distance."

There was a report on these sarsen stones at Salcombe Hill, regarding a field excursion led by Woodward and Ussher (1899).

"April 1st 1899. - Leaving Seaton soon after 9 a.m., the members were driven along the new Beer road and across the plateau of Chalk and Upper Greensand, by Stovar Long Lane to Holy Head ,419 ft.), and past Hangman's Stone (479ft.), to the top of Salcombe Hill (557 ft.). Here, alighting from the vehicles [horse-drawn carriages], they took the track leading by South Down Farm towards the brow of the cliffs. Attention was arrested by some large blocks of siliceous breccia, and these were presumed to be relics of former Eocene deposits which once spread across the area, and to which further reference was subsequently made. Long ago Mr. Godwin-Austen remarked on the resemblance of these blocks to greywethers ... The included fragments were angular, but, as Mr. Clement Reid had shown, the materials forming the Bagshot gravels were more and more angular as they were traced westwards.." [continues]

See also Bristow on sarsens at north of the Bovey Basin, Devon.

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Boulders, Salcombe Fishing Grounds, English Channel

Hunt (1880, 1881, 1883, 1885) found a considerable number of foreign blocks in the Salcombe fishing grounds, some 30 to 50 km south of the Devon coast. Of 40 blocks described, there is granite, microgranulite, serpentine, syenite, gabbro, diorite, basalt, "diabase" (dolerite), trachyte, gneiss, quartz grit, conglomerate, sandstone and chalk flints and other rock types. They are discussed further by Prestwich (1892). The serpentine is precisely like the Cornish varieties. Surprisingly the other igneous rocks could not with certainty be ascribed to the English or French coasts. The gneiss resembled Hebridean gneiss from Scotland.

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Dating of the Erratics

The erratics are beneath a raised beach and beneath fossiliferous clays in old channels and these relationships can help date them. At West Wittering laminated peaty clay with Corbicula lies above clayey gravel with erratics. This peaty clay yielded bones of Rhinoceras associated with land, freshwater, and a few marine shells; and seeds of plants (White, 1915). Reid (1899) recorded 94 species of plants with several undetermined forms that belong to no living British plants, and two Mediterranean species, Najas minor Allione and N. graminea Delile, now extinct in Britain. The known mollusca comprise 8 marine and 62 non-marine species, the later including Corbicula fluminalis (Mull.) and Paludestrina marginata (Mich), also extinct in these islands. In addition to the mammals already mentioned, there are the remains of water-vole (Microtus amphibius Linn.), frog (Rana temporaria Linn.), pike (Esox lucius Linn.) and eel (Anguilla vulgaris? Turton) according to Johnson (1901). The lower part of the deposit is purely freshwater; but the upper part contains many estuarine Hydrobia, occasional cockles (Cardium), and some salt-marsh plants (Reid, 1892). There may be continuity up into marine deposits which lie above, that is the main raised beach shingle.

Later work on Interglacial deposits of Selsey Bill, similar to these, is by West and Sparks (1960). They showed that these channel-fill sediments are of Ipswichian age, that is of the last or Eemian Interglacial. The raised beach deposits which overlie these are also of the Ipswichian Interglacial and are the result of a marine transgression. Thus the erratics were present before the deposition of the main Ipswichian raised beach. This is usually regarded as a 15 feet or roughly 5 metres raised beach, but as argued by West and Sparks it probably corresponds to a sea-level of plus 7.6 m. The stones are not younger than the Ipswichian but Kellaway (1975) regarded them as reworked at the beginning of the Interglacial at about 128,000 BP (before the present), and actually from a glacier of Wolstonian age ( approximately 195,000 to 128,000 BP) when sea-level was about minus 180 m.

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Grounding of Ice Floes?

Grounding of Ice-Floes in Sussex

An extensive study of the low-level (about 3m.) raised beaches was made by Prestwich in 1892. He considered that these raised beaches, now seen in certain places such as on the Isle of Portland and at Selsey Bill, once extended all along the south coast of England. Encroachment of the sea has destroyed great tracts of them. This map based on Prestwich's work shows the present West Sussex coastal plain that was submerged during the deposition of the low-level (Ipswichian) raised beach of the last Interglacial. This area is where the erratics occur and these were attributed by Prestwich to the stranding of ice-floes.

There has been disagreement, amongst the proponents of ice-floe transport, as to whether the blocks came from the east or the southwest. We will briefly consider the various ideas.

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Ice-Floes from France?

Sir Charles Lyell, in his classic textbook of 1871 argued for a French origin. He said:

"Erratics near Chichester. - The most southern memorials of ice-action and of a Post-pliocene fauna in Great Britain is on the coast of the county of Sussex, about 25 miles west of Brighton and 15 south of Chichester, a marine deposit exposed between high and low tide occurs on both sides of the promontory called Selsea Bill, in which Mr. Godwin-Austen found thirty-eight species of shells, and the number has since been raised to seventy.....

.... the sandy loam in which they occur is overlaid by yellow clayey gravel with large erratic blocks which must have been drifted into their present position by ice when the climate had become much colder. These transported fragments of granite, syenite, and greenstone, as well as of Devonian and Silurian rocks, may have come from the coast of Normandy and Brittany, and many of them are of such large size that we must suppose them to have been drifted into their present site by coast-ice. I measured one, at Pagham, 21 feet in circumference. In the gravel of this drift with erratics are a few littoral shells of living species, indicating an ancient coast-line. "

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Ice-Floes from the North Sea?

Early ideas about the boulders involved longshore drift in the past from Devon and Cornwall towards the Sussex coast. Godwin-Austen (1857) pointed that the large boulders could only have travelled long distances by floating ice and this could explain the occurrence of rock types that could be matched in the Contentin Peninsula of France, in Brittany and in the Channel Islands. He thought that some boulders could not be matched with French rocks, however. Codrington (1870) and Lyell (1871), as noted above, argued for a French origin involving floating ice. Prestwich (1892) considered that evidence of raised beaches in France showed that the Straits of Dover were not closed at the time of the low-level raised beaches. Granite, Palaeozoic and other pebbles found offshore at Ramsgate and in the English Channel between the Calvados and the Sussex coast were used by Prestwich to support a theory of transport by ice-bearing currents from the North Sea and through the Straits of Dover. He argued that there was a great bay which originally existed from Waterbeach, near Chichester to Bembridge and from Pagham to Portsea and this was at least 24 km long and 16 km wide. This would have had an extension to Brighton as shown on the map above. In this gulf ice-floes from the eastward would become embayed and stranded, and there dropped the blocks of granite and other rocks now found scattered over all that area (Prestwich, 1892). The Purbeck silicified wood is an apparent objection to this, but silicified wood of this age and type occurs in the Purbecks of the Boulonnais (a new study involving detailed comparison of Purbeck wood from Portland, the Boulonnais and Sussex would be useful) . Prestwich considered that most of the igneous, metamorphic and Palaeozoic rocks found off the Devon coast are derived from Norway.

Of particular interest is the comment of Prestwich (1890) that the "reddish sandstone blocks so common in Hayling Island, and now recorded by Mr. Hunt off the Devonshire coast, may have come from the shores of Denmark, North Germany, or Heligoland." But, however, he admitted that further investigation is necessary.

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Floating Ice at the Present Day

Floating ice occurs on a limited scale in the Solent area when there are particularly cold winters. See Rogers (1996, p. 95) for a photograph of ice fringing the beach at Clarence Pier, Southsea. In the early 1960s the author has similar sea ice on the Bournemouth beaches and walked across frozen Christchurch Harbour. A small iceberg was once reported off the Isle of Wight. In exceptionally cold spells some small-scale transportation by ice-floes may still take place.

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English Channel Glacier and Selsey Moraine Theory

Glacier and Selsey Moraine

In 1975, an important paper by Kellaway and co-authors put forward a theory of glacier development in the English Channel. In particular the authors argued for a Wolstonian glacier from the west leaving a moraine in the Selsey area. This is illustrated in the map which is just a modified section of a larger map with explanation provided in the paper. The paper is stimulating and needs careful study. It was not readily accepted for various reasons such as the lack of an obvious high area from which the glacier was descending. It is difficult to find much direct evidence for "Glacial Lake Solent". Nevertheless it is a good paper for new ideas and it is necessary to consider the erratics again in the light of these theories.

Kellaway, Redding, Shephard-Thorn and Destombes, 1975. Abstract:
"Several lines of evidence for former glaciation of the English Channel are considered. These include the following major geomorphological features: (1) extensive areas of flat featureless sea bed bounded by cliffs with residual steep-sided rock masses rising about 60-150m above them., (2) terrace forms bounded by breaks in slope or low cliffs, (3) palaeovalley systems attributed to present land drainage, (4) enclosed deeps (fosses); all except (3) may be attributed to a glacial origin. The distribution of erratics on the Channel floor and in modern and raised beaches of its coasts are attributed to widespread Saalian glaciation. This glaciation was responsible for the deposition of morainic material at Selsey and the damming-up of glacial Lake Solent. The so-called '100 foot raised beach' of west Sussex is now re-interpreted as a fluvioglacial deposit laid down at the northern margin of the English Channel ice.

It is thought that at the height of the Saalian glaciation mean sea-level fell to between 90 and 100 m below O.D. and that for a time the ice was grounded near the western margin of the continental shelf. Possible reconstructions of the limits and main movements of the Weichselian and Saalian ice sheets covering the British Isles and English Channel are included. " End of abstract.

In the Introduction the authors state that in their account they attempt to show that the English Channel has been subject to one or more Quaternary glaciations. They claim that the non-glacial pagadigm which has dominated geomorphology in southern England for over a century has achieved little in explaining the relations of the inland surfaces to the evolution of the coastline and adjacent sea floor. "The crude concept of 'periglacial southern Britain' is out of date, but by including the Celtic Sea, Bristol Channel and English Channel in the glaciated area we take a step which may require modification of the theories relating to the formation and behaviour of ice sheets formed on continental shelves by heavy precipitation in strongly oceanic regions".

They mention that the flat bedrock surface of much of the English Channel is like a flat, glaciated terrain. Specific evidence includes: (a). The presence of closed depressions such as the Fosse Central or Hurd Deep. There is a deep closed depression on the floor of Plymouth Sound. The full discussion as to why these were considered to be of glacial origin is not given here, but should be consulted by specialists interested in this topic. Landslides at Axmouth (Devon), the Isle of Wight and Eastbourne are attributed to glacial oversteepening. Hills of the Somerset and Severn estuary such as Glastonbury Tor and Brent Knoll have been oversteepened and this can be attributed to ice action. (b). The presence of the erratics discussed in this webpage and others in southern Britain. Reference is made to the specific occurrences in Sussex and Hampshire described above. Kellaway et al. (1975) considered that there are two principal suites of foreign rocks in the raised and low-level beaches on the northern shores of the English Channel (there is mention of three suites but actually two are described):

1. Erratics from Brittany, the Channel Islands and the Cotentin Peninsula, with greywether sandstone (sarsen) and some Upper Jurassic, Cretaceous and Tertiary rocks . These are the erratics of the Hampshire - Sussex coastal plain discussed here.
2. Erratics of western or northwestern origin. These are on the Dorset coast and further west, and include the Portland raised beaches and the Chesil Beach. The material includes the Budleigh Salterton quartzites and rocks of more distant origin. In southwest England, a large example of interest is the Giants Rock of Porthleven (Flett, 1946), a boulder of about 50 tonnes, is derived from NW Scotland or some adjacent part of the sea floor.

Kellaway et al. (1975) argued that the boulders of the Bognor - Portsmouth area cannot have been introduced by floating ice in Eemian (Ipswichian) or post-Eemian times, and the position of the inland boulders is such that they could only have arrived in floating ice at some very much earlier period. It is a valid point that the water depth in the Hamphire - Sussex coastal plain area would have been very shallow and shelving during the time of depostion of the raised beach and this would have made it difficult for floating ice to have transported the boulders far towards the land at the time. It is also difficult to see how, since sea level seems to have been related to climate, with low sea-levels during glacials, how floating ice could have occurred in quantity at a time of relatively high sea level and mild climate, the Eemian or Ipswichian Interglacial. An origin of the boulders by the transporting action of an earlier glacier is attractive, but so too is the possibility of the transport of the boulders by floating ice at a date before the Interglacial. An overall general fall in sea levels during the Quaternary makes this feasible.

A part of the English Channel glacier theory is that some gravels in the Solent area are of fluvioglacial origin (Kellaway et al. 1975). This has been dismissed by Keen (1980). He found that the composition of the gravels shows no evidence of far-travelled material such as would be expected to occur had they been deposited as outwash, and said that "a glacial contribution to the gravels must be discounted". The precise confinement of the erratics to the low coastal plain, and a lack of erratics further inland also seems to be evidence against a glacier and is more easily explained by a sea-level control. In the Kellaway et al. paper a discussion contribution by Turner (p. 217) argues that the Boxgrove - Slindon Raised Beach is not of fluvioglacial origin as the English Channel Glacier theory requires. Green (1973) had previously produced firm sedimentological evidence against a Kellaway (1971) that a glacier was involved in the transport of stones from Stonehenge.

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The English Channel glacier theory is interesting and stimulating but it is not strongly supported by firm evidence. It does not accord with the evidence of the flint gravels, there is no evidence for a "Glacial Lake Solent". The erratics were probably mostly transported by floating sea ice. There is clearly is a problem concerning dates of transport of the erratics and relative sea-levels. A phase of ice-floes, significantly earlier than the Eemian (Ipswichian) Interglacial accounts most satisfactorily for most features. The source of the erratics of the Hamphire-Sussex coastal plain seems to have been largely the south or southwest, the coasts of Brittany, the Cotentin Peninsula and the Channel Islands, but some more rocks of more distant origin seem to be present.

Some sarsens may have been transported by ice or flood action in the braided rivers of the periglacial environment. This may explain examples at Milford and other places away from the raised beach, unless these (low) area were still within reach of sea-ice. The higher level sarsens of Portland require further consideration; they are somewhat mysterious but there is a possible source area on the chalk downs northwest of Weymouth from which they could have been transported in some way. However, the deposit in which they occur is not sufficiently understood and the possibility of a high level raised beach on Portland has not been eliminated.

The erratics of the low-level Hampshire-Sussex coastal plain were transported to the area earlier than 128 thousand years BP at an unknown date. They were present near the surface during the Devensian. In the early Flandrian those on the present coastal plain and others under the sea to the south or in the channel of the Solent were also on dry land. The deeper ones were submerged round about about 8000 BP and large areas south of Hayling Island, for example, in post-Neolithic times. The erratics include sarsens (greywethers) particularly just east and southeast of the Solent, but the known examples are smaller than the stones of Stonehenge, and often weathered and crumbly to some extent. Dolerite, like the Stonehenge Bluestones, does not seem to have been recorded. There is no evidence that the sarsen stones were transported into the area by man and ice was the agent. Evidence has not yet been presented that any sarsens or other rock types from here were used in any way in connection with Stonehenge, but equally there is no evidence against. They were used in wall-construction in historic times.

Studies of the examples of erratics offshore could shed new light on the theories of ice-transport and date of origin. Unusual rock types might more clearly indicate the source areas. Any possible evidence of human is clearly worth seeking.

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I would like to thank Dr Ken Collins for valuable discussion on the erratics. John Barber has kindly provided specimens for study. Dr Patrick Friend has given helpful information with regard to Chichester Harbour. Mrs. G.A. Holloway has kindly informed me about the present and past locations of the "Three Stones", sarsen stones of Titchfield, and sent photographs for which I am very grateful. I am very much obliged to Gary Manning for the photograph of a sarsen stone emerging from Chilling Cliff.

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References and Select Bibliography

See also: Geological Bibliography of the Solent Estuarine System.

Allen , L.G. and Gibbard, P.L. 1993. Pleistocene evolution of the Solent River of southern England. Quaternary Science Reviews, Elsevier, 12, 503-528. Authors are both from the Subdepartment of Quaternary Research, Botany School, University of Cambridge, Downing Street, Cambridge, CB2 3EA, UK. Abstract: The Solent River no longer exists since most of its course was drowned by eustatic sea level rise during the Flandrian Stage (Holocene). Previously, it flowed eastwards across southeast Dorset and south Hampshire as an extension of the River Frome. As such, it formed the axial major stream of the Hampshire Basin. A sequence of fluvial aggradations, ranging in height from 125 m O.D. to below sea level, provide evidence of the former courses of this substantial river and its tributaries. Detailed study of the deposits, supported by analysis of clast lithological assemblages provide the basis for the recognition of a series of lithostratigraphical units throughout the area. The facies and sedimentary structures indicate that the bulk of the deposits accumulated in a braided river environment under periglacial climates. Late Pleistocene fossiliferous sediments of Ipswichian and Flandrian age provide a biostratigraphical framework.The results demonstrate that the Solent River was a substantial system, comparable in size to the present Thames, and was a tributary ofthe 'Channel River' during periods of low sea level (cold stages). Evolution of the river reflects its response to climatic change, local geological structure and long term tectonic activity. Although datable deposits limit determination of the age of the Solent River sequence, it is undoubtedly of considerable antiquity and potentially extends back to the Early Pleistocene. Discussion of the sequence includes placing the events within their regional context. [End of abstract. - Notes: This is an important paper on the Pleistocene deposits of the southern Hampshire Basin. Many gravel terraces are recognised and named, but are not correlated in detail with the numbered terraces of the British Geological Survey (Southampton and Bournemouth sheets). The paper includes discussion of the following gravel terraces in the Bournemouth-Southampton area from lowest to highest: Pennington Gravel (Pennington near Lymington, and with Ipswichian Interglacial deposits); Lepe Lower Gravel (Lepe Beach, under the Interglacial deposit, pre-Ipswichian); North End Copse / Holdenhurst Gravel; Pennington Gravel / Burton Rough Gravel/ Southbourne Gravel; ; Lepe Upper Gravel (Lepe Beach, Devensian); Milford-on-Sea Gravel / Bransgore Gravel /Knighton Lodge Gravel; Stanswood Bay Gravel / West Southbourne Gravel / Taddiford Farm Gravel / High Cliff Gravel / Ensbury Park Gravel; Tom's Down Gravel (near Fawley); Old Milton Gravel; Mount Pleasant Gravel; Setley Plain Gravel (New Forest); Beaulieu Heath Gravel (New Forest); Tiptoe Gravel; Sway Gravel; Holmsley Ridge Gravel (western New Forest); Whitefield Hill Gravel. The Wareham-Dorchester Pleistocene gravels are also discussed. The paper includes interesting data on gravel composition, mostly flint and chert and including the presence of Portland Rhaxella chert and oolitic chert and Upper Greensand chert.]

Allen, L.G., Gibbard, P.L., Pettit, M.E., Preece, R.C. and Robinson, J.E. 1996. Late Pleistocene interglacial deposits at Pennington Marshes, Lymington, Hampshire, southern England. Proceedings of the Geologists' Association, London, vol. 107, 39-50. By Lorraine G. Allen, Phillip L. Gibbard, Mary E. Pettit, Richard C. Preece and J. Eric Robinson (First three authors from the Subdepartment of Quaternary Research, Botany School, University of Cambridge; Preece from University Museum of Zoology, University of Cambridge and Robinson from Department of Geology, University College, London.). Abstract: Fossiliferous organic sediments interstratified within fluvial gravels at Pennington Marshes, Lymington, have been recovered in boreholes and investigated. The organic deposit, here defined as the Pennington Organic Bed, occurs between -3.9 to -5.3 m OD and has been traced 200 m across the immediate area. Pollen analyses indicate a temperate flora of interglacial character. Molluscan and ostracod assemblages contain no brackish elements and are typical of a shallow, freshwater stream or abandoned channel. A change from an aquatic to a terrestrial molluscan fauna indicates progressive drying out of the water body. The Pennington Organic Bed cannot be confidently attributed to any particular stage, but since it occurs within a lower terrace than that at Stone Point, 15 km to the NE, it is probably younger and an early Ipswichian age (Ip Ha?) is suggested. The Pennington Lower Gravel, below the organic deposit, is therefore probably Wolstonian and the Pennington Upper Gravel, above them, Devensian in age. The estuarine interglacial deposits at Stone Point, previously believed to have been Ipswichian, are likely to belong to an earlier stage. It is possible, although less likely, that they accumulated during a later part of the Ipswichian as the transgression aggraded to the level of the higher terrace surface. Similarly, if the gravels at Stone Point resulted from a tributary river, rather than the Solent River itself, this could also explain the altimetric differences and allow the organic deposits to be attributed to different parts of the same stage. However, there is no evidence to support either of these alternative possibilities.
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Bates, M.R. , Parfitt, SA and Roberts, M.B. 1997. The chronology, palaeogeography and archaeological significance of the marine Quaternary record of the West Sussex coastal plain, southern England, UK. Quaternary Science Reviews, 16, 1227-1252.

Bates, M.R. 2001. The meeting of the waters: raised beaches and river gravels of the Sussex coastal plain / Hampshire Basin. In: Wenban-Smith, F.F. and Hosfield, R.T. (Editors) 2001. Palaeolithic Archaeology of the Solent River. Lithic Studies Society Occasional Paper, No. 7, 2001, 111pp. Proceedings of the Lithic Studies Society day meeting held at the Department of Archaeology, University of Southampton on Saturday 15th January 2000.
Integrating Pleistocene sediments from continental systems and the marine stratigraphic record is a key objective for Quaternary science. In many cases correlation of these records is only possible through comparison of proxy records. However, this objective may be realised in those areas of the world where marine marginal sediments occur in close proximity to terrestrial fluvial deposits in the lower reaches of major river valleys. One such location is the Sussex/Hampshire corridor in southern England. Pleistocene sediments within the area of the former Solent River system and the West Sussex Coastal Plain are evidence for a wide variety of different depositional systems ranging from temperate flood plains and marine beaches to cold climate braided river channels. These deposits may contain archaeological material such as handaxes as well as faunal and floral remains. The proximity of sediments of both temperate and cold climate types within the lower reaches of the modern major river valleys should allow correlation between the temperate and cold climate stratigraphic records in this area. This evidence may be used to link the marine and fluvial stratigraphic records. This paper describes the nature of the different types of evidence from the Sussex/Hampshire corridor and considers some of the problems and pitfalls in the use of this information in the construction of an integrated stratigraphic frameworkfor the area.
Belderson , R.H., Kenyon, N.H. and Wilson, J.B. 1973. Iceberg plough marks in the north east Atlantic. Palaeogeography, Palaeoclimatology, Palaeoecology, 13, 215-224.
Bowen , H.C. and Smith, I.F. 1977. Sarsen stones in Wessex: the Society's first investigations in the evolution of the landscape project. The Antiquaries Journal, 57, 185-196.
Bristow , C.M. 1993. Silcrete duricrusts west of the Bovey Basin. Proceedings of the Ussher Society, ISSN 0566-3954, 1993, vol. 8, no. 2, pp. 177-180 (25 references). By C.M. Bristow, Camborne school mines, Cornwall TR15 3SE.
Abstract: Siliceous duricrusts ("silcretes") produced by the precipitation of silica in a weathering environment have been described from south-east Devon by Isaac. Precipitation of silica is also evidenced by the Woolley Grit north of Bovey Tracey, presumed to be of early Tertiary age, which is a sequence of sands and gravels which have been cemented by chalcedonic silica. Further east, in south Somerset and on the chalk uplands surrounding the Hampshire Basin, there is extensive evidence of silcrete (sarsen) formation, which is also thought to be of Palaeogene age. Recent exposures on the south side of the Bovey Basin at Ringslade ball clay pit have shown a number of large boulders of what appears to be silcrete/ferricrete duricrust up to 3 m in diameter, occurring in the Ringslade fault zone where upper Devonian slate is thrust over the Bovey Formation.
[See also Woodward (1889) on sarsens at Salcombe Hill, Devon]
Bustillo, M.A. and Bustillo, M. 2000. Miocene silcretes in argillaceous playa deposits, Madrid Basin, Spain; petrological and geochemical features. Sedimentology, Vol. 47, No. 5, 1023-1037.

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Carruthers , W. 1885. Notes on fossil roots in the sarsen stones of Wiltshire. Geological Magazine, 22, 361-363.
Clark , M.J., Lewin, J. and Small, R.J. 1967. The sarsen stones of the Marlborough Downs and their geomorphological implications. Southampton Research Series in Geography, 4, 3-40.
Codrington , T. 1870. On the superficial deposits of the south of Hampshire and the Isle of Wight. Quarterly Journal of the Geological Society, London, 26, 528-551.

Cordiner , R. 2006. The Quaternary Geology of Chichester Harbour. By Roger J. Cordiner of Bognor Regis, West Sussex. Geode Publications, Bognor Regis, September 2006. A copy can be ordered from Roger Cordiner, 39 Devonshire Road, Bognor Regis, West Sussex, PO21 2SY for £6 plus 1.50 p & p. [This contains good information on erratics in the Chichester Harbour area with discussion about their origins.] For enquiries about the booklet please contact: cordinerroger@live.co.uk

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Davies , K.H. 1985. The Aminostratigraphy of British Pleistocene Beach Deposits. Unpublished Ph.D. Thesis, University of Wales, Aberystwyth.
Edwards, R.A . and Freshney, E.C. 1987. British Geological Survey, Geological Map, Sheet 315 (England and Wales), Southampton, Solid and Drift, 1:50,000 (new edition). Described by the Edwards and Freshney (1987) memoir on the Geology of the Country around Southampton.

Edwards, R.A. and Freshney, E.C. 1987. Geology of the Country around Southampton . Memoir for 1:50,000 geological map sheet 315 (England and Wales). British Geological Survey, Natural Environment Research Council, Her Majesty's Stationery Office, London, 111pp. ISBN 0 11 884396 6. Original Price - £7.50. Contributors: Geophysics - Smith, I.F.; Palaeontology: Boulter, M.C., Clark, R.D., Cooper, J., Harland, R., Hughes, M.J. and King, C.; Petrography - Merriman, R.J. and Morton, A.C.; Stratigraphy: Holder, M.T., King, C. and Scrivener, R.C.; Water Supply - Monkhouse, R.A. [This is the key Geological Survey publication on Southampton and adjacent area, including part of the New Forest. It is an almost A4 size, slim, green, paperback book with BGS - Southampton on the side. It is present in Southampton University, Hartley Library, the National Oceanographic Library, Southampton Oceanography Centre and probably in many university and local public libraries. It is easily obtainable and may still be in print.]
Everard , C.E. 1954. The Solent river; a geomorphological study. Transactions of the Institute of British Geographers, 20, 41-58.

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Fisher , O. 1871. Portland wood, on the coast of Sussex. Reply to Mr. Perceval. Geological Magazine, 8, 524-525.
Flett , J.S. 1946. Geology of the Lizard and Meneage (2nd Edition). Memoirs of the Geological Survey of Great Britain.
Godwin-Austen , R.A.C. 1857. On the newer Tertiary deposits of the Sussex coast. Quarterly Journal of the Geological Society, London, 13, p.56.
Green , C.P. 1973. Pleistocene river gravels and the Stonehenge problem. Nature, London, 243, 214-216.

Green, C.P. 1997. Stonehenge: geology and prehistory. Proceedings of the Geologists' Association, 108, 1-10.
Hepworth , J. 1998. Aspects of the English silcretes and comparison with some Australian occurrences. Proceedings of the Geologists' Association, 109, 271-288.
Hodgson , J.M. 1964. The low-level Pleistocene marine sands and gravels of the west Sussex coastal plain. Proceedings of the Geologists' Association, London, 75, 547-561.
Hopson , P.M. 2000. Geology of the Fareham and Portsmouth District, A brief explanation of the geological map Sheet 316 Fareham and part of Sheet 331 Portsmouth. British Geological Survey.
Hunt, A.R., 1880, 1881, 1883, 1885. On the submarine geology of the English Channel off the coast of south Devon. Transactions of the Devon Association.
Irving , A. 1898. Excursion to Bishop's Stortford, Saturday, July 17th, 1897. Proceedings of the Geologists' Association, London, v. 15, 193-197. (see also p. 236). Extract from p. 196: "The 'Herts Puddingstone'. - Very fine examples were seen and examined in the grounds of Oak Hall... Since the director came into this part of the country he has recognised in these [puddingstones] mere pebbly varieties of Sarsen Stones.. In Berk and Surrey we meet with such masses as agglutinated portions of the Bagshot Pebble-bed at St. Anne's Hill, Surrey (A. Irving, Quarterly Journal of the Geological Society, vol. 43, pp. 376, 377), the largest such block being seen on the hill-slope and known in folk-lore as 'Monk's Grave'.."
Johnson , J.P. 1901. The Pleistocene fauna of West Wittering. Proceedings of the Geologists' Association, London, 17, 261-264.
Judd , J.W. 1901. Note on the structure of sarsens. Geological Magazine, New Series, 8, 1-2.
Keen , D.H. 1980. The environment of deposition of the south Hampshire Plateau Gravels. Proceedings of the Hampshire Field Club and Archaeological Society, 36, 15-24.
Kellaway , G.A. 1971. Glaciation and the stones of Stonehenge. Nature, London, vol. 233, September 3, pp. 30-35.

Kellaway, G.A., Redding, J.H., Shephard-Thorn, E.R. and Destombes, J-P. 1975. The Quaternary history of the English Channel. Philosophical Transactions of the Royal Society, London, Series A, 279, 189-218. In: Dunham, K., and Smith, A.J. 1975. A Discussion on the Geology of the English Channel. The Royal Society, 6 Carlton House Terrace, London, SW1Y 5AG.
Kennard , A.S. and Woodward, B.B. 1901. The Post-Pliocene non-marine mollusca of the south of England. Proceedings of the Geologists' Association, p. 244 and Table opp. p. 268.
Leckie , D.A. and Cheel, R.J. 2006. Nodular silcretes of the Cypress Hills Formation (upper Eocene to middle Miocene) of southern Saskatchewan, Canada. Sedimentology, Vol. 37, Issue 3, pp. 445-454. By D.A. Leckie and R.J. Cheel, Institute of Sedimentary and Petroleum Geology, Geological Survey of Canada, 3303 33rd St NW, Calgary, Alberta, Canada, T2L 2A7 and Department of Geological Sciences, Brock University, St Catharines, Ontario, Canada, L2S 3A1.
Siliceous nodules in the upper Eocene to middle Miocene Cypress Hills Formation in southern Saskatchewan formed on the distal portions of an extensive braidplain. The nodules are similar to silcretes described elsewhere in the literature but their morphology and occurrence suggests that they are of a rare variety. The silcretes are discrete equant to disc-shaped nodules, 1–3 cm thick, and up to 15 cm long. The silicretes form horizontal, discontinous layers parallel to bedding within an unweathered profile. Void spaces and fractures within the nodules are lined or filled with drusy quartz. The silcretes contain less than 0.07% TiO2. The TiO2/SiO2/Al2O3 and TiO2/SiO2/Fe2O3 ratios are similar to values obtained from nodules formed in an arid to semi-arid environment based on comparison with modern silcretes. This interpretation is confirmed by independent sedimentological and palaeontological climatic evidence for an arid to semi-arid climate throughout Oligocene time in the western Canadian plains.
Lyell , C. 1871. The Student's Elements of Geology. John Murray, London, 624 pp.
Martin , E. C. 1938. The Littlehampton and Portsdown Chalk inliers and their relation to the raised beaches of West Sussex. Proceedings of the Geologists' Association, 34, 253.
Nash , D.J., Shaw, P.A. and Ullyot, J.S. 1998. Drainage-line silcretes of the Middle Kalahari: an analogue for Cenozoic sarsen trains. Proceedings of the Geologists' Association, 109, 241-254.
This paper describes models put forward to explain the development of silcretes within drainage lines at the distal end of the Okavango Delta system in the Middle Kalahari of Botswana, and proposes that they provide an analogue for the formation of sarsen stones within sarsen trains. The models describe silcrete formation in shallow pans situated within river valleys, with silicification resulting from the accumulation of fluvial inputs of clastic material, silica from groundwater and additions of silica phytoliths from aquatic vegetation in seasonal pools. It is suggested, on the basis of macro- and micromorphological comparisons, that sarsens in the Clatford Bottom area of Wiltshire formed by this mechanism. The sarsens would have originally formed a spatially-limited linear silcrete body and would have then accumulated within contemporary valleys during the course of landscape evolution. The implications of this model for the environmental conditions associated with sarsen formation and the likely timing of silicification are subsequently discussed. It is concluded that the geomorphological setting of sarsen formation may have been more important than climatic conditions at the time(s) of silicification.
Nicholls , W.T. 1866. Remarks on some "Sarsens", or erratic blocks of stone found in the gravel, in the neighbourhood of Southampton, Hampshire. Geological Magazine, 3, 296-298. Sarsen stones at Bevois Valley gravel pit, Southampton and elsewhere in the region.
Palmer , L.S. and Cooke, J.H. 1923. The Pleistocene deposits of the Portsmouth district and their relation to man. Proceedings of the Geologists' Association, 34, 253 - 282.
Parfitt , S.A., Owen, F. and Keen, D.H. 1998. Pleistocene stratigraphy, vertebrates and Mollusca, Black Rock, Brighton. In: Murton, J.B., Whiteman, C.A., Bates M.R., Bridgland, D.R., Long, A.J., Roberts, M.B. and Waller, M.P.; eds. The Quaternary of Kent and Sussex. Quaternary Research Association, Cambridge, 146-150.
Potter , J.F. 1998. The distribution of silcretes in the churches of the London Basin. Proceedings of the Geologists' Association, 109, 293-304.
Preece, R.C., Scourse, J.D., Houghton, S.D., Knudsen, K.L. and Penny, D.N. 1990. The Pleistocene sea-level and neotectonic history of the eastern Solent, southern England. Philosophical Transactions of the Royal Society of London, B328, 425-477.
Prestwich , J. 1875. Notes on the phenomena of the Quaternary period in the Isle of Portland and around Weymouth. Quarterly Journal of the Geological Society, London, 31, 29-54. [Raised beach, landslides, beef and middle Purbeck detritus at Portland Bill, Chesil Beach, vertebrate remains in fissures, the Portland Mammaliferous Drift etc.]

Prestwich, J. 1892. The raised beaches, and 'Head' or rubble-drift, of the south of England: their relation to the valley drifts and to the Glacial Period; and on a late post-Glacial submergence. Quarterly Journal of the Geological Society, London, 48, 263-343.
Reid , C. 1892. The Pleistocene deposits of the Sussex coast, and their equivalents in other districts. Quarterly Journal of the Geological Society, London, 48, 344-364.

Reid, C. 1899. Origin of the British Flora. (book). See pp. 94-96.

Reid, C. 1897. The Geology of the Country around Bognor. Memoirs of the Geological Survey of Great Britain.

Reid, C. 1902. The Geology of the Country around Southampton. Memoirs of the Geological Survey of Great Britain.

Reid, C. 1903. The Geology of the Country near Chichester. Memoirs of the Geological Survey of Great Britain.
Rogers , P. 1996. Portsmouth and Southsea. Britain in Old Photographs. Sutton Publishing Ltd., 126pp. ISBN 0-7509-1296-0.
Shaw , P.A. and Nash, D.J. 1997. Dual mechanisms for the formation of fluvial silcretes in the distal reaches of the Okavango Delta fan, Botswana. Earth Surface Processes and Landforms. Vol. 23, Issue 8, pp. 705-714. By Paul A. Shaw and David J. Nash ( Department of Environmental Science, University of Luton, Park Square, Luton LU1 3JU, UK and Earth and Environmental Science Research Unit, University of Brighton, Mithras House, Lewes Road, Brighton BN2 4AT, UK)
Silcretes exposed within river-marginal or valley settings have been described in a number of studies, but few models have been suggested for the development of these fluvial silcretes. An exception is that proposed by McCarthy and Ellery (Journal of Sedimentary Research, 1995, Vol. A65, pp. 77-90) to describe mechanisms of early stage near-surface silica diagenesis in the Okavango Delta, Botswana. This paper describes the characteristics and possible origins of massive surface and sub-surface silcretes at Samedupe and Boro Junction, beyond the distal margin of the Okavango Delta and further downstream than the sites described by McCarthy and Ellery. Morphological and petrological evidence from surface exposures and three sedimentary cores suggests that other modes of formation may also be applicable. A dual model of formation is proposed: surface silcretes are suggested to have developed by silica accumulation in seasonal pools remaining after the annual Okavango flood, whilst sub-surface horizons appear to have formed under conditions of varying pH associated with fluctuating groundwater levels beneath the channel floor. This model is reviewed in the context of the fluvial silcrete debate.
Small , R.J., Clark, M.J. and Lewin, J. 1970. The periglacial rock stream at Clatford Bottom, Marlborough Downs, Wiltshire. Proceedings of the Geologists' Association, 81, 87-98.
Smith , B. 1936. Levels in the raised beach, Black Rock, Brighton. Geological Magazine, 73, 423.
Solly , H.S. 1910. Note on a large boulder found at Branksome, Upper Parkstone. Proceedings of the Dorset Natural History and Antiquarian Field Club, 31, 161-164. (by the Reverend H. Shaen Solly, M.A.).

Strahan , A. 1898. The Geology of the Isle of Purbeck and Weymouth. Memoirs of the Geological Survey, England and Wales. London. 278pp. Published by Order of the Lords Commissioners and Her Majesty's Treasury. Price 10 shillings and 6 pence. Printed for Her Majesty's Stationery Office, by Wyman and Sons, Limited, Fetter Lane, EC. With coloured map, cross-sections and a bibliography of books, papers and maps by W. Whitaker, F.R.S. (1761-1873) and by A. Strahan, M.A. (1874 -1898).
Summerfield , M.A. and Goudie, A.S. 1980. The sarsens of southern England: their palaeoenvironmental interpretation with reference to other silcretes. In: Jones, D.K.C., ed., The Shaping of Southern England. Institute of British Geographers, Special Publication, 11, Academic Press, London, 71-100.
Thiry , M. and Marechal, B. 2001. Development of Tightly Cemented Sandstone Lenses in Uncemented Sand: Example of the Fontainebleau Sand (Oligocene) in the Paris Basin. By Médard Thiry and Benoît Marécha. Journal of Sedimentary Research, May 2001, vol. 71, no. 3, pp. 473-483.
In the Fontainebleau Sand (Oligocene), superposed lenses of sandstone result from a silicification process controlled by the watertable during the recent geomorphologic evolution of the landscape. The most outstanding feature of these silicified bodies is the contrast they show between the very hard, tightly cemented sandstone and the loose and permeable embedding sand. This pattern raises the question of the growth mechanism of the lenses. The lenses are composed of tightly quartz-cemented sandstone with well-developed quartz overgrowths. Cathodoluminescence of the sandstones shows detrital grains with subeuhedral quartz overgrowths and isopachous quartz rims surrounding the detrital grains or the overgrowths. The isopachous rims suggest amorphous or poorly ordered silica deposits that later recrystallized into quartz. The syntaxial overgrowths and the silica deposits alternate in a sequential way on a centimeter scale and reflect variations in the physicochemical characteristics of the feeding groundwater. The mechanism of the silica deposition is probably complex and can only be hypothesized. Whatever the mechanism, it appears from the arrangement of the sandstone layers that silica precipitation occurred near the watertable and at the interface between regional groundwater and local recharge water. Silica precipitation along an interface may explain the sharp boundary between cemented sandstone and loose sand.
The cementation was modeled with the coupled reaction-transport code METIS. The model was constrained with permeability values, hydraulic gradient, and dissolved silica contents measured in the Fontainebleau Sand. The simulation reproduced the characteristics and morphologies shown by the sandstone lenses in the field. It shows the importance of a high groundwater flow rate to provide the silica necessary for cementation of the sandstones in a time span compatible with the geological constraints. The conventionally accepted kinetics of quartz precipitation did not result in simulating cementation of the sandstone lenses in a geologically reasonable time frame. To overcome this constraint, it was necessary to increase the kinetic reaction rate about 1,000 times, which agrees with the amorphous silica deposits observed in the Fontainebleau Sandstones.
Ullyott , J.S. and Nash, D.J. 2006. Micromorphology and geochemistry of groundwater silcretes in the eastern South Downs, UK. Sedimentology, Vol. 53, No. 2, 387–412. By J. Stewart Ullyott and David J. Nash.

Ullyot, J.S., Nash, D.J. and Shaw, P.A. 1998. Recent advances in silcrete research and their implications for the origin and palaeoenvironmental significance of sarsens. Proceedings of the Geologists' Association, London, 109, 255-270.
Sarsens and puddingstones have long been recognised as varieties of silcrete and were, until recently, considered to have formed under hot sub-tropical or tropical climates in tectonically stable, low relief landscapes during the early Palaeogene. This paper provides a summary of the major advances in silcrete research since the most recent review of sarsen development and focuses upon models of silcrete genesis derived from studies in France, Australia and the Kalahari region of southern Africa. These models include silcretes which formed within soil profiles by pedogenic processes (pedogenic silcretes), those which formed in zones of groundwater outflow or water table fluctuation in association with drainage-lines or in lacustrine settings (groundwater or drainage-line silcretes), and more complex cases where silcretes developed through the interaction of more than one set of processes through time (multiphase and intergrade silcretes). Each of these models is subsequently placed within a landscape context through consideration of a series of case studies. The implications of this recent research for the interpretation of UK sarsens and puddingstones are discussed. The importance of identifying the mode or modes of origin of any silicified remnant materials before drawing any conclusions concerning their age, extent and possible palaeoenvironmental significance is stressed.

Ullyott, J.S., Whiteman, C.A. and Nash, D.J. 2000. Field meeting: landscape evolution in the eastern South Downs, with particular reference to sarsens and Quaternary deposits, Saturday 17 October, 1998. Proceedings of the Geologists' Association, London, 111, 91-96.
West , I.M. 1980. Geology of the Solent Estuarine System. In; The Solent Estuarine System: an Assessment of Present Knowledge, N.E.R.C. Publication. Series C. No. 22 , November 1980. pp 6-18.
West, R.G . and Sparks, B.W. 1960. Coastal interglacial deposits of the English Channel. Philosophical Transactions of the Royal Society of London, Series B., Biological Sciences, No. 701, Vol. 243, pp. 95-133, 27th October, 1960, with an Appendix on the Mammalia by A.T. Sutcliffe. Published by the Royal Society, Burlington House, Piccadilly, London W1. Communicated by H. Godwin, F.R.S. Addresses of authors: R.G. West - Subdepartment of Quaternary Research, University of Cambridge; B.W. Sparks, Department of Geography, University of Cambridge. Abstract: Fossiliferous Late-Pleistocene deposits on the foreshore of the English Channel at Selsey (Sussex), Stone (Hampshire), and near Arromanches (Calvados), have been investigated. At each site analyses of pollen, macroscopic plant remains and Mollusca have been made and from these vegetational, faunal, environmental and climatic conditions have been reconstructed. ... At Selsey, it is shown that the deposits, which lie in a channel cut in Eocene rocks, are of Ipswichian (Eemian or Last) Interglacial age. Pollen analysis of the sediments of the channel filling show that they formed during zones b, c, d, e and f of this interglacial, which show the succcession from open parkland vegetation to birch-, to pine, to oak-dominated forests. Analysis of the macroscopic plant remains and of the molluscs suggests a rapid climatic amelioration at the beginning of the interglacial, so that by the beginning of zone f there are indications of summer warmth exceeding that of the present day in the area. In the upper part of the channel filling, estuarine deposits overlie freshwater deposits. It is shown that the marine transgression causing the change was taking place in zone f and was probably responsible later for the raised beach deposits which overlie the channel deposits and form the cliff at Selsey Bill. ... At Stone pollen analysis shows that brackish water deposits, below present high tide level were formed in zone f of the Ipswichian Interglacial. At that time Quercus, Pinus, and Acer were the chief trees forming the forest in that region. The macroscopic plant remains and the Mollusca indicate that the deposit was formed under saltmarsh conditions. As at Selsey, the raised beach gravel found overlying the interglacial deposit is related to the same marine transgression that produced the brackish water conditions... Near Arromanches, at St Come de Fresne and Asnelles-Belle-Plage, two deposits showing a change from marine to freshwater sediments were investigated. The analysis of pollen and the Mollusca showed the prevalence of pine forest and its replacement by open steppe-like conditions as the marine regression occurred. After the regression, limon covered the freshwater deposits. The fossiliferous deposits are tentatively correlated with zone i of the Eemian Interglacial... The relative land and sea-level changes indicated by the deposits are considered. It is concluded that in the English Channel, during the Ipswichian (Eemian) Interglacial, sea-level rose above its present height in zone f and fell below it during zone i. The Selsey-Brighton raised beach and the Normannien II raised beach are correlated with the same marine transgression. It is pointed out that if the Selsey-Brighton raised beach is to be correlated with the Monastirian II level of 7-8m, then this level should be correlated with the Ipswichian (Eemian) Interglacial. [end of abstract.]

West, R.G. 1967. The Quaternary of the British Isles. In "The Quaternary" Vol. 2 (K. Randama, ed.), 187. Wiley, New York.

West, R.G. 1972. Relative land sea level changes in southeastern England during the Pleistocene. Philosophical. Transactions of the Royal Society, London, A272, 87-97.
Whitaker , W. 1862. On the grey wethers of Wiltshire. Quarterly Journal of the Geological Society, London, 18, 271-274.
White , H.J.O. 1915. The Geology of the Country near Lymington and Portsmouth. Memoirs of the Geological Survey of England and Wales. H.M.S.O., London. Explanation of Sheets 330 and 331 (mainland).
Woodward , H.B. and Ussher, W.A.E. 1899. Excursion to Seaton, Sidmouth, and Exeter. Proceedings of the Geologists' Association, London, vol. 16, pp. 133-153. By Horace B. Woodward, F.R.S., F.G.S. and W.A.E. Ussher, F.G.S.
[See also Bristow on sarsens at north of the Bovey Basin, Devon]

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Sarsen Stones and Stonehenge - some selected Internet Links

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Some Relevant Webpage Links

AboutStonehenge.Info AboutStonehenge.Info provides Stonehenge information, pictures, legends, and lore including theories on construction, purposes, and age for both students and tourists.

Stonehenge |

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Copyright © 2014 Ian West, Catherine West, Tonya Loades and Joanna Bentley. All rights reserved. This is a purely academic website and images and text may not be copied for publication or for use on other webpages or for any commercial activity. A reasonable number of images and some text may be used for non-commercial academic purposes, including field trip handouts, lectures, student projects, dissertations etc, providing source is acknowledged.

Disclaimer: Geological fieldwork involves some level of risk, which can be reduced by knowledge, experience and appropriate safety precautions. Persons undertaking field work should assess the risk, as far as possible, in accordance with weather, conditions on the day and the type of persons involved. In providing field guides on the Internet no person is advised here to undertake geological field work in any way that might involve them in unreasonable risk from cliffs, ledges, rocks, sea or other causes. Not all places need be visited and the descriptions and photographs here can be used as an alternative to visiting. Individuals and leaders should take appropriate safety precautions, and in bad conditions be prepared to cancell part or all of the field trip if necessary. Permission should be sought for entry into private land and no damage should take place. Attention should be paid to weather warnings, local warnings and danger signs. No liability for death, injury, damage to, or loss of property in connection with a field trip is accepted by providing these websites of geological information. Discussion of geological and geomorphological features, coast erosion, coastal retreat, storm surges etc are given here for academic and educational purposes only. They are not intended for assessment of risk to property or to life. No liability is accepted if this website is used beyond its academic purposes in attempting to determine measures of risk to life or property.

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Dr Ian West, author of these webpages

Webpage - written and produced by:

Ian West, M.Sc. Ph.D. F.G.S.


at his private address, Romsey, Hampshire, kindly supported by Southampton University,and web-hosted by courtesy of iSolutions of Southampton University. The website does not necessarily represent the views of Southampton University. The website is written privately from home in Romsey, unfunded and with no staff other than the author, but generously and freely published by Southampton University. Field trips shown in photographs do not necessarily have any connection with Southampton University and may have been private or have been run by various organisations.